Family told NBC affiliate WWBT that Martin was trying to defend his sister when he was fatally struck, possibly with a brick. He died at the scene, while his sister was taken to the hospital, where she was still recovering Friday.

Police declined to detail the attack or the severity of the girl’s injuries.

But Dionne Waugh, a spokeswoman for the Richmond police, told NBC News that outraged neighbors helped cops track down the alleged assailant.

“The community’s response has been tremendous,” Waugh said Friday.

— Erik Ortiz

Martin Cobb, an 8-year-old Richmond, Va., boy was beaten to death trying to defend his 12-year-old sister from a brutal rape, police and relatives said.Family photo via WWBT